Manufacturing process for papermaking belts using 3D printing technology

ABSTRACT

A papermaking belt including zones of material laid down successively using a 3D printing process. The zones include at least a pocket zone configured to form three dimensional structures in a paper web by applying vacuum to pull the paper web against the pocket zone. In at least one exemplary embodiment, the zone also include at least one vacuum breaking zone configured to limit an amount of paper fibers pulled through the pocket zone by the applied vacuum.

RELATED APPLICATIONS

This application is a non-provisional based on U.S. Provisional PatentApplication No. 62/240,924, filed Oct. 13, 2015 and U.S. ProvisionalPatent Application No. 62/088,095, filed Dec. 5, 2014, the contents ofwhich are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

This invention relates to the manufacturing process of belts used inpapermaking processes.

BACKGROUND

Tissue papermaking is a complex process where specific control overproduct quality attributes is critical. Arguably, the most criticalpieces of equipment used to control these quality attributes are thefabrics utilized on the papermaking machines. The various papermakingmachine technologies are conventional dry crepe, through air drying(TAD), or hybrid technologies such as Metso's NTT, Georgia Pacific'sETAD, or Voith's ATMOS process. All these technologies utilize fabricsat various stages in the process to influence tissue web properties andoverall asset productivity.

The predominant manufacturing method for making a tissue web is theconventional dry crepe process. The major steps of the conventional drycrepe process involve stock preparation, forming, pressing, drying,creping, calendering (optional), and reeling the web.

The first step of stock preparation involves selection, blending,mixing, and preparation of the proper ratio of wood, plant, or syntheticfibers along with chemistry and fillers that are needed in the specifictissue grade. This mixture is diluted to over 99% water in order toallow for even fiber formation when deposited from the machine headboxinto the forming section. There are many types of forming sections usedin conventional papermaking (inclined suction breast roll, twin wireC-wrap, twin wire S-wrap, suction forming roll, and Crescent formers)but all are designed to retain the fiber, chemical, and filler recipewhile allowing the water to drain from the web. In order to accomplishthis, fabrics are utilized.

Forming fabrics are woven structures that utilize monofilaments (yarns,threads) composed of synthetic polymers (usually polyethylene,polypropylene, or nylon). The forming fabric has two surfaces: the sheetside and the machine or wear side. The wear side is in contact with theelements that support and move the fabric and are thus prone to wear. Toincrease wear resistance and improve drainage, the wear side of thefabric has larger diameter monofilaments compared to the sheet side. Thesheet side has finer yarns to promote fiber and filler retention on thefabric surface.

In order to control other properties such as: fabric stability, lifepotential, drainage, fiber support, and clean-ability, different weavepatterns are utilized. Generally, forming fabrics are classified by thenumber of layers utilized in their construction. There are three basicstyles of forming fabrics: single layer, double layer, and triple layer.A single layer fabric is composed of one CD (shute) and one MD (warp)yarn system. The main problem of single layer fabrics is lack ofdimensional stability. The double layer forming fabric has one layer ofwarp yarns and two layers of shute yarns. This multilayer fabric isgenerally more stable and resistant to stretching. Triple layer fabricshave two separate single layer fabrics bound together by separated yarnscalled binders. Usually the binder fibers are placed in cross directionbut also can be oriented in the machine direction. Triple layer fabricshave further increased dimensional stability, wear potential, drainage,and fiber support as compared to single or double layer fabrics.

The conventional manufacturing of forming fabrics includes the followingoperations: weaving, initial heat setting, seaming, final heat setting,and finishing. The fabric is made in a loom using two interlacing setsof monofilaments (or threads or yarns). The longitudinal threads arecalled the warp and the transverse called shute threads. After weaving,the forming fabric is heated to relieve internal stresses to enhancedimensional stability of the fabric. The next step in manufacturing isseaming. This step converts the flat woven fabric into an endlessforming fabric by joining the two MD ends of the fabric. After seaming,the final heat setting is applied to stabilize and relieve the stressesin the seam area. The final step in the manufacturing process isfinishing, where the fabric is cut to width and sealed.

There are several parameters and tools used to characterize theproperties of the forming fabric: mesh and count, caliper, frames, planedifference, open area, air permeability, void volume and distribution,running attitude, fiber support, drainage index, and stacking. None ofthese parameters can be used individually to precisely predict theperformance of a forming fabric on a paper machine, but together theexpected performance and sheet properties can be estimated.

After web formation and drainage (to around 35% solids) in the formingsection (assisted by centripetal force around the forming roll, andvacuum boxes in several former types), the web is transferred to a pressfabric upon which the web is pressed between a rubber or polyurethanecovered suction pressure roll and Yankee dryer. The press fabric ispermeable fabric designed to uptake water from the web as it is pressedin the press section. It is composed of large monofilaments ormulti-filamentous yarns, needled with fine synthetic batt fibers to forma smooth surface for even web pressing against the Yankee dryer.

After pressing the sheet, between a suction pressure roll and a steamheated cylinder (referred to as a Yankee dryer), the web is dried fromup to 50% solids to up to 99% solids using the steam heated cylinder andhot air impingement from an air system (air cap or hood) installed overthe steam cylinder. The sheet is then creped from the steam cylinderusing a steel or ceramic doctor blade. This is a critical step in theconventional dry crepe process. The creping process greatly affectssoftness as the surface topography is dominated by the number andcoarseness of the crepe bars (finer crepe is much smoother than coarsecrepe). Some thickness and flexibility is also generated during thecreping process. If the process is a wet crepe process, the web must beconveyed between dryer fabrics through steam heated after-dryer cans todry the web to the required finished moisture content. After creping,the web is optionally calendered and reeled into a parent roll and readyfor the converting process.

The through air dried (TAD) process is another manufacturing method formaking a tissue web. The major steps of the through air dried processare stock preparation, forming, imprinting, thermal pre-drying, drying,creping, calendering (optional), and reeling the web. The stockpreparation and forming steps are similar to conventional dry creping.

Rather than pressing and compacting the web, as is performed inconventional dry crepe, the web undergoes the steps of imprinting andthermal pre-drying. Imprinting is a step in the process where the web istransferred from a forming fabric to a structured fabric (or imprintingfabric) and subsequently pulled into the structured fabric using vacuum(referred to as imprinting or molding). This step imprints the weavepattern (or knuckle pattern) of the structured fabric into the web. Thisimprinting step has a tremendous effect on the softness of the web, bothaffecting smoothness and the bulk structure. The design parameters ofthe structured fabric (weave pattern, mesh, count, warp and weftmonofilament diameters, caliper, air permeability, and optionalover-laid polymer) are; therefore, critical to the development of websoftness. The manufacturing method of an imprinting fabric is similar toa forming fabric, expect for the addition of an overlaid polymer. Thesetype of fabrics are disclosed in patents such as U.S. Pat. Nos.5,679,222; 4,514,345; 5,334,289; 4,528,239; and 4,637,859, thedisclosures of which are hereby incorporated by reference in theirentirety. Essentially, fabrics produced using these methods result in afabric with a patterned resin applied over a woven substrate. Thebenefit is that resulting patterns are not limited by a woven structureand can be created in any desired shape to enable a higher level ofcontrol of the web structure and topography that dictate web qualityproperties.

After imprinting, the web is thermally pre-dried by moving hot airthrough the web while it is conveyed on the structured fabric. Thermalpre-drying can be used to dry the web to over 90% solids before it istransferred to a steam heated cylinder. The web is then transferred fromthe structured fabric to the steam heated cylinder though a very lowintensity nip (up to 10 times less than a conventional press nip)between a solid pressure roll and the steam heated cylinder. The onlyportions of the web that are pressed between the pressure roll and steamcylinder rest on knuckles of the structured fabric; thereby, protectingmost of the web from the light compaction that occurs in this nip. Thesteam cylinder and an optional air cap system, for impinging hot air,then dry the sheet to up to 99% solids during the drying stage beforecreping occurs. The creping step of the process again only affects theknuckle sections of the web that are in contact with the steam cylindersurface. Due to only the knuckles of the web being creped, along withthe dominant surface topography being generated by the structuredfabric, and the higher thickness of the TAD web, the creping process hasmuch smaller effect on overall softness as compared to conventional drycrepe. After creping, the web is optionally calendered and reeled into aparent roll and ready for the converting process. Some TAD machinesutilize fabrics (similar to dryer fabrics) to support the sheet from thecrepe blade to the reel drum to aid in sheet stability and productivity.Patents which describe creped through air dried products include U.S.Pat. Nos. 3,994,771; 4,102,737; 4,529,480; and 5,510,002.

A variation of the TAD process where the sheet is not creped, but ratherdried to up to 99% using thermal drying and blown off the structuredfabric (using air) to be optionally calendered and reeled also exits.This process is called UCTAD or un-creped through air drying process.U.S. Pat. No. 5,607,551 describes an uncreped through air dried product.

A new process/method and paper machine system for producing tissue hasbeen developed by the Voith GmbH (Heidenheim, Germany) and is beingmarketed under the name ATMOS. This process/method and paper machinesystem has several patented variations, but all involve the use of astructured fabric in conjunction with a belt press. The major steps ofthe ATMOS process and its variations are stock preparation, forming,imprinting, pressing (using a belt press), creping, calendering(optional), and reeling the web.

The stock preparation step is the same as a conventional or TAD machinewould utilize. The purpose is to prepare the proper recipe of fibers,chemical polymers, and additives that are necessary for the grade oftissue being produced, and diluting this slurry to allow for proper webformation when deposited out of the machine headbox (single, double, ortriple layered) to the forming surface. The forming process can utilizea twin wire former (as described in U.S. Pat. No. 7,744,726) a CrescentFormer with a suction Forming Roll (as described in U.S. Pat. No.6,821,391), or preferably a Crescent Former (as described in U.S. Pat.No. 7,387,706). The preferred former is provided a slurry from theheadbox to a nip formed by a structured fabric (inner position/incontact with the forming roll) and forming fabric (outer position). Thefibers from the slurry are predominately collected in the valleys (orpockets, pillows) of the structured fabric and the web is dewateredthrough the forming fabric. This method for forming the web results in aunique bulk structure and surface topography as described in U.S. Pat.No. 7,387,706 (FIG. 1 through FIG. 11). The fabrics separate after theforming roll with the web staying in contact with the structured fabric.At this stage, the web is already imprinted by the structured fabric,but utilization of a vacuum box on the inside of the structured fabriccan facilitate further fiber penetration into the structured fabric anda deeper imprint.

The web is now transported on the structured fabric to a belt press. Thebelt press can have multiple configurations. The first patented beltpress configurations used in conjunction with a structured fabric isU.S. Pat. No. 7,351,307 (FIG. 13), where the web is pressed against adewatering fabric across a vacuum roll by an extended nip belt press.The press dewaters the web while protecting the areas of the sheetwithin the structured fabric valleys from compaction. Moisture ispressed out of the web, through the dewatering fabric, and into thevacuum roll. The press belt is permeable and allows for air to passthrough the belt, web, and dewatering fabric, into the vacuum rollenhancing the moisture removal. Since both the belt and dewateringfabric are permeable, a hot air hood can be placed inside of the beltpress to further enhance moisture removal as shown in FIG. 14 of U.S.Pat. No. 7,351,307. Alternately, the belt press can have a pressingdevice arranged within the belt which includes several press shoes, withindividual actuators to control cross direction moisture profile, (seeFIG. 28 in U.S. Pat. No. 7,951,269 or 8,118,979 or FIG. 20 of U.S. Pat.No. 8,440,055) or a press roll (see FIG. 29 in U.S. Pat. No. 7,951,269or 8,118,979 or FIG. 21 of U.S. Pat. No. 8,440,055). The preferredarrangement of the belt press has the web pressed against a permeabledewatering fabric across a vacuum roll by a permeable extended nip beltpress. Inside the belt press is a hot air hood that includes a steamshower to enhance moisture removal. The hot air hood apparatus over thebelt press can be made more energy efficient by reusing a portion ofheated exhaust air from the Yankee air cap or recirculating a portion ofthe exhaust air from the hot air apparatus itself (see U.S. Pat. No.8,196,314). Further embodiments of the drying system composed of the hotair apparatus and steam shower in the belt press section are describedin U.S. Pat. Nos. 8,402,673, 8,435,384 and 8,544,184.

After the belt press is a second press to nip the web between thestructured fabric and dewatering felt by one hard and one soft roll. Thepress roll under the dewatering fabric can be supplied with vacuum tofurther assist water removal. This preferred belt press arrangement isdescribed in U.S. Pat. No. 8,382,956, and U.S. Pat. No. 8,580,083, withFIG. 1 showing the arrangement. Rather than sending the web through asecond press after the belt press, the web can travel through a boostdryer (FIG. 15 of U.S. Pat. No. 7,387,706 or 7,351,307), a high pressurethrough air dryer (FIG. 16 of U.S. Pat. No. 7,387,706 or 7,351,307), atwo pass high pressure through air dryer (FIG. 17 of U.S. Pat. No.7,387,706 or 7,351,307) or a vacuum box with hot air supply hood (FIG. 2of U.S. Pat. No. 7,476,293). U.S. Pat. Nos. 7,510,631, 7,686,923,7,931,781 8,075,739, and 8,092,652 further describe methods and systemsfor using a belt press and structured fabric to make tissue productseach having variations in fabric designs, nip pressures, dwell times,etc. and are mentioned here for reference. A wire turning roll can alsobe utilized with vacuum before the sheet is transferred to a steamheated cylinder via a pressure roll nip (see FIG. 2a of U.S. Pat. No.7,476,293).

The sheet is now transferred to a steam heated cylinder via a presselement. The press element can be a through drilled (bored) pressureroll (FIG. 8 of U.S. Pat. No. 8,303,773), a through drilled (bored) andblind drilled (blind bored) pressure roll (FIG. 9 of U.S. Pat. No.8,303,773), or a shoe press (U.S. Pat. No. 7,905,989). After the webleaves this press element to the steam heated cylinder, the % solids arein the range of 40-50%. The steam heated cylinder is coated withchemistry to aid in sticking the sheet to the cylinder at the presselement nip and also aid in removal of the sheet at the doctor blade.The sheet is dried to up to 99% solids by the steam heated cylinder andinstalled hot air impingement hood over the cylinder. This dryingprocess, the coating of the cylinder with chemistry, and the removal ofthe web with doctoring is explained in U.S. Pat. Nos. 7,582,187 and7,905,989. The doctoring of the sheet off the Yankee, creping, issimilar to that of TAD with only the knuckle sections of the web beingcreped. Thus the dominant surface topography is generated by thestructured fabric, with the creping process having a much smaller effecton overall softness as compared to conventional dry crepe.

The web is now calendered (optional,) slit, and reeled and ready for theconverting process.

The ATMOS manufacturing technique is often described as a hybridtechnology because it utilizes a structured fabric like the TAD process,but also utilizes energy efficient means to dewater the sheet like theConventional Dry Crepe process. Other manufacturing techniques whichemploy the use of a structured fabric along with an energy efficientdewatering process are the ETAD process and NTT process. The ETADprocess and products can be viewed in U.S. Pat. Nos. 7,339,378,7,442,278, and 7,494,563. This process can utilize any type of formersuch as a Twin Wire Former or Crescent Former. After formation andinitial drainage in the forming section, the web is transferred to apress fabric where it is conveyed across a suction vacuum roll for waterremoval, increasing web solids up to 25%. Then the web travels into anip formed by a shoe press and backing/transfer roll for further waterremoval, increasing web solids up to 50%. At this nip, the web istransferred onto the transfer roll and then onto a structured fabric viaa nip formed by the transfer roll and a creping roll. At this transferpoint, speed differential can be utilized to facilitate fiberpenetration into the structured fabric and build web caliper. The webthen travels across a molding box to further enhance fiber penetrationif needed. The web is then transferred to a Yankee dryer where it can beoptionally dried with a hot air impingement hood, creped, calendared,and reeled. The NTT process and products can be viewed in internationalpatent application publication WO 2009/061079 A1. The process hasseveral embodiments, but the key step is the pressing of the web in anip formed between a structured fabric and press felt. The webcontacting surface of the structured fabric is a non-woven material witha three dimensional structured surface comprised of elevations anddepressions of a predetermined size and depth. As the web is passedthrough this nip, the web is formed into the depression of thestructured fabric since the press fabric is flexible and will reach downinto all of the depressions during the pressing process. When the feltreaches the bottom of the depression, hydraulic force is built up whichforces water from the web and into the press felt. To limit compactionof the web, the press rolls will have a long nip width which can beaccomplished if one of the rolls is a shoe press. After pressing, theweb travels with the structured fabric to a nip with the Yankee dryer,where the sheet is optionally dried with a hot air impingement hood,creped, calendared, and reeled.

As shown in the aforementioned discussion of tissue papermakingtechnologies, the fabrics utilized are critical in development of thetissue web's structure and topography which are instrumental in thequality characteristics of the web such as softness (bulk softness andsurfaces smoothness) and strength (tensile). The manufacturing processfor making these fabrics has been limited to weaving a fabric (primarilyforming fabrics and imprinting/structured fabrics) or a base structureupon which synthetic fibers are needled (press fabrics) or overlaid witha polymeric resin (overlaid imprinting/structured fabrics).

SUMMARY OF THE INVENTION

An object of the present invention is to provide a manufacturing processfor belts used in papermaking processes, and more specifically toprovide a process of using three dimensional printing technology(3D-printing) to produce belts used in tissue paper production.

Another object of the present invention is to provide a manufacturingprocess for papermaking belts in which polymers of specific materialproperties are laid down in an additive manner under computer control tocreate belts with unique structural and topographical profiles.

Another object of the present invention is to allow for selectivedepositing of preferred polymer materials across the belt structureadvantageously.

Another object of the present invention is to allow for blending ofpolymers in defined zones to provide functionality not capable withconventional belt-making processes. The printing process allows eachelement of the belt to be designed in localized areas.

According to an exemplary embodiment of the present invention, a methodfor making a three dimensional papermaking belt configured for use informing, pressing, drying or molding of fibrous web, comprises formingthe belt by 3D printing.

According to another exemplary embodiment of the present invention, amethod of making a papermaking belt comprises: laying down successivelayers of material using a 3D printing process so as to form a unitarystructure with zones corresponding to the successive layers, wherein thezones comprise: a pocket zone configured to form three dimensionalstructures in a paper web by applying vacuum to pull the paper webagainst the pocket zone; and at least one vacuum breaking zoneconfigured to limit an amount of paper fibers pulled through the pocketzone by the applied vacuum.

A papermaking belt according to an exemplary embodiment of the presentinvention comprises: zones of material laid down successively using a 3Dprinting process, wherein the zones comprise: a pocket zone configuredto form three dimensional structures in a paper web by applying vacuumto pull the paper web against the pocket zone; and at least one vacuumbreaking zone configured to limit an amount of paper fibers pulledthrough the pocket zone by the applied vacuum.

Other features and advantages of embodiments of the invention willbecome readily apparent from the following detailed description, theaccompanying drawings and the appended claims.

DESCRIPTION OF THE DRAWINGS

The features and advantages of exemplary embodiments of the presentinvention will be more fully understood with reference to the following,detailed description when taken in conjunction with the accompanyingfigures, wherein:

FIG. 1 is a planar view of a papermaking belt according to an exemplaryembodiment of the present invention;

FIG. 2 is another planar view of the papermaking belt of FIG. 1;

FIG. 3A is planar view of a papermaking belt according to an exemplaryembodiment of the present invention;

FIG. 3B is another planar view of the papermaking belt of FIG. 3A;

FIG. 4 is a cross-sectional view of a papermaking belt according to anexemplary embodiment of the present invention; and

FIGS. 5A-5C are cross-sectional views showing various steps of a methodof forming a papermaking belt according to an exemplary embodiment ofthe present invention.

DETAILED DESCRIPTION

The present invention is directed to a process of using threedimensional printing technology (3D-printing) to produce belts intendedfor use in tissue paper production. The process involves laying downpolymers of specific material properties in an additive manner undercomputer control to create belts with unique structural andtopographical profiles.

3D printing is widely use in the automotive industry, engineering, art,architecture and even in research for creating components requiring highlevel of precision. As conventionally known, the process involves theuse of CAD software to generate a model, which is then transferred toprocess preparation software where the model is virtually disassembledinto individual layers. Molds are placed in a virtual build space, andthe building process is started. The loose basic material is evenlyapplied over the entire build width. A print head applies binder wherethe model is to be produced, whereby the binder infiltrates the recentlyapplied layer and connects it with the layer below. The buildingplatform is lowered and the process starts again. Following thecompletion of the building process, the loose particle material isremoved manually. Once the molds have been cleaned, they can be mountedand prepared for casting.

Current methods for manufacturing papermaking fabrics lack versatilityand are limited in their scope. In the current invention, papermakingfabrics are manufactured using any 3D printing techniques and thematerials that can be utilized with these 3D printers. This process canbe used to manufacture any papermaking fabrics including but not limitedto forming, press, belt press, imprinting/structured fabrics, dryerfabrics, sheet support fabrics, or belt press fabric. The main 3Dprinting techniques include Fused Deposition Modeling™ (commonly knownas fused filament fabrication) and PolyJet Technology (Stratasys Ltd,Eden Prairie, Minn., USA) which is described below in detail, but othermethods such as Selective Laser Melting (SLM), Direct Metal LaserSintering (DMLS), Selective Laser Sintering (SLS), Stereolithography(SLA), or Laminated Object Manufacturing (LOM) can be utilized. Thevarious materials that can be utilized on these printers are alsodescribed below.

A key aspect of this invention is the process of printing the entirebelt with at least two different zones. One zone is a vacuum breakingzone that prevents or limits the amount of fibers pulled through thestructured tissue pocket. The second zone is the pocket zone. The pocketzone shapes the tissue sheet into the desired three dimensional shapes.Because the entire belt is printed with advanced materials, the totalthickness of the bend can be significantly reduced as compared toconventional belts. Such advanced materials includes materials thatcannot be used in conventional belt manufacturing due to inherentprocess limitations. Aspects of the present invention allow alternativematerials to be used in unique ways within the context of belt-makingprocesses. For example, individual elements in the belts can be formedwith different materials. Specific examples of such elements include asquare element having dimensions of 1000 microns×1000 microns withdifferent layers of polymers and elements that have 20 to 40 microlayers of polyethylene, polypropylene, PAE resins, C—F functional grouppolymers, etc. The elements can be “coated” (i.e., an outer layer can beprinted on the element) with different cross-linking polymers (20-40microns). Such use of unique belt-making materials and dimensions is notpossible in conventional processes, such as polymer casting, molding orextrusions.

The present invention allows for the design of belt elements that resultin one or more of the following: elimination of the need forlubrications on belts, such as TAD release; use of more of the pocketelement without leaving fibers behind (higher bulk with thinner overallfabric; this is particularly important with controlling vacuum andpocket shapes); paper pocket shapes and dimensions that can not beformed by conventional processes due to coefficient of friction andother surface properties of conventional fabrics and belts.

The 3D printing process described herein also allows for printing of abelt with three zones: pocket, vacuum breaker, and valley pocket supportzones. The valley pocket support zone prevents the formation of pinholes at the bottom of each pocket which helps to control airpermeability, tissue pocket formation and fiber pocket delamination.

A four layer belt can also be formed with pocket, vacuum breaker, valleypocket support and shear modulus control zones. The shear moduluscontrol zone enables the entire belt to flex over CD and MD directionsto prevent belt failure. This zone allow the belt to compress withoutchanging pocket dimensions, and it allows the belt to flex in sheardirections. The shear modulus control zone may be formed by selectivedeposition of polymers selected to match structural requirements forthis zone. The printing process allows for mixing of material betweenzones to ensure continuation of load stresses across the matrix. Thisinvention provides an entire belt in a homogenous and unitary form thatsignificantly improves fabric life and paper properties. It should beappreciated that the number and arrangement of zones of the inventive 3Dprinted belt is not limited to those described herein, and other than apocket zone, no other zones are specifically required

The current invention also allows for the production of seamed andnon-seamed belts. Seams used in conventional belt design (lock or keyand pin joints) can be used, but non-seamed belts may also be formed inwhich the belt is printed continuously in the Z direction (i.e., in anadditive manner).

FIGS. 1 and 2 are planar views of a portion of a papermaking fabric,generally designated by reference number 1, according to an exemplaryembodiment of the present invention. The fabric 1 is made using a 3Dprinting process and in particular the entire fabric 1 is printed withat least two different zones that are laid on top of one another duringthe printing process. For the purposes of the present invention, theterm “zone” is defined as a section of the fabric that extendscontinuously (with our without openings) across the length and width ofthe fabric and at least partially through the thickness of the fabric,where each zone is configured to provide the fabric with a correspondingperformance characteristic. In an exemplary embodiment, one zone is avacuum breaking zone 10 (shown facing upwards in FIG. 1) which preventsor limits the amount of fibers pulled through the structured tissuepocket, and another zone is a pocket zone 12 (facing upwards in FIG. 2)which includes a plurality of pockets 14. The pockets 14 shape thetissue sheet into the desired three dimensional shapes. Because theentire belt is printed with advanced materials, the total thickness ofthe belt can be significantly reduced. In exemplary embodiments, thefabric 1 may have more than two zones, and in a particular embodimenthas multiple (i.e., two or more) vacuum breaker zones and a structuredtissue pocket zone.

As shown in FIGS. 1 and 2, the vacuum breaking zone 10 and pocket zone12 are each made up of a crisscross pattern of material. The pattern ofthe vacuum breaking zone 10 is angled relative to the pocket zone 12 sothat vacuum breaker elements cross under the pocket layer at or near thecenter of a corresponding pocket 14. In an exemplary embodiment, theelements of the vacuum breaking zone 10 are cylindrical shaped so as topresent curved edges at the point of contact with a vacuum box withinthe papermaking manufacturing line. The thickness of the vacuum breakingzone 10 preferably makes up less than 50% of the total thickness of thefabric 1 as measured in cross section, and more preferably makes up lessthan 30% of the total thickness. In an exemplary embodiment, the vacuumbreaker zone 10 has a surface energy within the range of 37 to 60dyne/cm.

Although the open areas or pockets 14 of the pocket zone 12 are shown inFIGS. 1 and 2 with a generally square shape, it should be appreciatedthat the pockets 14 may have any other suitable shape, including, forexample, oval or diamond shapes. In this regard, the pockets 14 may havestraight or curved edges. In an exemplary embodiment, the pocket zoneopen areas are formed by raised elements each with a cross sectionhaving a generally curved or dome-like shape. Also, in an exemplaryembodiment, the pocket zone 12 has a surface energy within the range of16 to 36 dyne/cm

In an exemplary embodiment, the entire fabric 1 has a caliper less than1 mm. The caliper of the fabric 1 is reduced less than 5% after 350,000cycles under a press load of 20 to 100 kN/m.

The papermaking fabric 1 is made using a 3D printing process that laysdown successive layers or zones of material. Each layer has a thicknesswithin the range of 1 to 1000 microns, and preferably within the rangeof 7 to 200 microns. The materials used in each layer may be composed ofpolymers with a Young's Modulus within the range of 10 to 500 MPa, andpreferably 40 to 95 MPa. Such polymers may include nylons, aramids,polyesters such as polyethylene terephthalate or polybutyrate, orcombinations thereof.

In an exemplary embodiment, the open area of the fabric 1 (i.e., theamount of air in the fabric as compared to amount of polymer) may bewithin the range of 10 to 95 percent, and preferably within the range of40 to 60 percent. The air permeability of the fabric 1 may be in therange of 100 to 1000 cubic feet per minute, and preferably within therange of 400 to 700 cubic feet per minute.

In an exemplary embodiment, the width of the fabric 1 may be within therange of 40 to 400 inches, and preferably within the range of 200 to 240inches. The caliper of the fabric 1 may be within the range of 0.25 to4.00 mm, and preferably within the range of 0.75 to 1.5 mm.

FIGS. 3A and 3B are planar views of a fabric, generally designated byreference number 100, according to another exemplary embodiment of thepresent invention. As in the previous embodiment, the fabric 100 ismanufactured by a 3D printing process in which successive zones ofmaterial are laid down to form a unitary fabric structure. The fabric100 includes a vacuum breaking zone 120 (shown facing upwards in FIG.3B) and a pocket zone 110 (facing upwards in FIG. 3A) which includes aplurality of pockets 112. Further, a valley pocket support zone 130 isformed at the bottom of each pocket 112. The valley pocket support zone130 may be formed as elements that together form a separate layer belowthe pocket zone 110 or the individual elements may form the bottomsurface of the pocket zone 112. The valley pocket support zone 130 maybe formed of a material that is different from the material used to formthe pocket zone 112 and which provides specific structural advantages.For example, the valley pocket support zone 130 may prevent theformation of pin holes at the bottom of each pocket 112 which helps tocontrol air permeability, tissue pocket formation and fiber pocketdelamination.

FIG. 4 is a cross sectional view of a fabric, generally designated byreference number 200, according to another exemplary embodiment of thepresent invention. As in the previous embodiments, the fabric 200 ismanufactured by a 3D printing process in which successive zones ofmaterial are laid down to form a unitary fabric structure. The fabric200 includes a vacuum breaking zone 220 and a pocket zone 210 whichincludes a plurality of pockets (not shown). Further, the fabric 200includes a shear modulus control zone 230 disposed between the pocketzone 210 and the vacuum breaking zone 220. As shown in FIG. 4, the shearmodulus control zone 230 includes solid portions 232 spaced apart byrelatively larger openings 234 which allow for the entire fabric 200 (asa unitary structure) to compress with little to no change in pocketdimensions and to flex in shear directions to prevent fabric failure.

In exemplary embodiments, the fabric is preferably made using FusedDeposition Modeling™ (FDM), also known as fused filament fabrication, orPolyjet Technology.

Fused Deposition Modeling™ (FDM) builds concept models, functionalprototypes and end-use parts in standard, engineering-grade andhigh-performance thermoplastics. 3D printers that run on FDM Technologybuild parts layer-by-layer by heating thermoplastic material to asemi-liquid state and extruding it according to computer-controlledpaths. Thermoplastic filament feeds through a heated head and exits,under high pressure, as a fine thread of semi-molten plastic. In aheated chamber, this extrusion process lays down a continuous bead ofplastic to form a layer. This layering process repeats to manufacturethermoplastic parts. FDM uses two materials to execute a print job:modeling material, which constitutes the finished piece, and supportmaterial, which acts as scaffolding. Material filaments are fed from the3D printer's material bays to the print head, which moves in X and Ycoordinates, depositing material to complete each layer before the basemoves down the Z axis and the next layer begins. Once the 3D printer isdone building, the user breaks the support material away or dissolves itin detergent and water, and the part is ready to use. The benefits ofFDM are: simple-to-use, office-friendly 3D printing process.Thermoplastic parts can endure exposure to heat, chemicals, humid or dryenvironments, and mechanical stress. Soluble support materials make itpossible to produce complex geometries and cavities that would bedifficult to build with traditional manufacturing methods.

PolyJet 3D printing is similar to inkjet document printing, but insteadof jetting drops of ink onto paper, PolyJet 3D printers jet layers ofliquid photopolymer onto a build tray and cure them with UV light. Acarriage—with four or more inkjet heads and ultraviolet (UV)lamps—traverses the work space, depositing tiny droplets ofphotopolymers, materials that solidify when exposed to UV light. Afterprinting a thin layer of material, the process repeats until a complete3D object is formed. Fully cured models can be handled and usedimmediately, without additional post-curing. Along with the selectedmodel materials, the 3D printer also jets a gel-like support materialspecially designed to uphold overhangs and complicated geometries. It iseasily removed by hand and with water. PolyJet 3D printing technologyhas many advantages for rapid prototyping, including superior qualityand speed, high precision, and a very wide variety of materials. Thebenefits of PolyJet technology create precision prototypes that set thestandard for finished-product realism. It's very thin print layers makecomplex shapes, fine details and smooth finished surfaces possible.

PolyJet offers product realism across a wide band of requirements. Thereare over 450 options offering a range of hues, transparency, strength,rigidity and flexibility. For FDM material options range from thecommonly used plastic to the highly advanced resin. Material optionsinclude: anti-static, FST rating (flame, smoke and toxicity), chemicalresistance and very high temperature resistance. Both FDM and PolyJetoffer bio-compatible materials with USP Plastic Class VI to ISO 10993ratings.

FIGS. 5A-5C are cross-sectional views showing a method of forming apapermaking belt according to an exemplary embodiment of the presentinvention. After the computer modeling is completed, as shown in FIG.5A, an initial layer of material is extruded or printed to form asupport or scaffolding layer 400. The scaffolding layer 400 is intendedto be a sacrificial layer that is later removed from the finished beltand which has the purpose of supporting subsequent layers that aresuccessively layered over or adjacent to the scaffolding layer 400. Inan exemplary embodiment, the scaffolding layer 400 may includeprotrusions 401 that form the pockets in the pocket zone to besubsequently printed over the scaffolding layer 400. The scaffoldinglayer 400 may be formed with other protrusions and/or indentations asneeded to aid in the formation of complementary structural elements insubsequently printed layers. It should be appreciated that thescaffolding layer is not necessary, and in other exemplary embodimentsthe papermaking belt may be 3D printed without the use of a scaffoldinglayer. In exemplary embodiments, gel material (e.g., acrylic acidpolymer gel) may be used to support the pocket and other structuresformed in the belt to prevent the structures from collapsing before theyare cured.

As shown in FIG. 5B, a second layer of material is printed or extrudedover the scaffolding layer 400 to form a pocket zone 402. The pocketzone 402 includes pockets that conform to the protrusions 401 extendingfrom the scaffolding layer 400, as well any other structurescomplementary to those formed in the scaffolding layer 400.

As also shown in FIG. 5B, a third layer of material is printed orextruded over the pocket zone 402 to form another layer, such as, forexample, a vacuum breaker zone 404. In other embodiments, a shearmodulus control zone and/or a valley pocket support zone may be layeredonto the pocket zone 402 prior to printing of the vacuum breaker zone404. In general, various layers are successively printed so as to forman integral and unitary structure in the form of a papermaking belt.

As shown in FIG. 5C, the scaffolding layer 400 is removed to expose thefinished papermaking belt structure. Any suitable technique may be usedto remove the scaffolding layer 400 (and other support layers that wererequired during the build process) including, for example, manualremoval, water jet and/or a chemical bath (for example, a bath of sodiumhydroxide).

While particular embodiments of the invention have been illustrated anddescribed, it would be obvious to those skilled in the art that variousother changes and modifications may be made without departing from thespirit and scope of the invention. It is therefore intended to cover inthe appended claims all such changes and modifications that are withinthe scope of this invention.

The invention claimed is:
 1. A method for making a three dimensionalpapermaking belt configured for use in forming, pressing, drying ormolding of fibrous web, wherein the process comprises forming the beltby 3D printing of a polymeric material having a Young's Modulus of 40 to95 MPa.
 2. The method of claim 1, wherein the papermaking belt isconfigured for use on a through air dried or un-creped through air driedpapermaking machine.
 3. The method of claim 1, wherein the 3D printingcomprises Fused Deposition Modeling (FDM) or PolyJet Technology.
 4. Themethod of claim 1, wherein the 3D printing comprises laying downsuccessive layers of material.
 5. The method of claim 4, wherein thelayers have a thickness of 1 to 1000 microns.
 6. The method of claim 4,wherein the layers have a thickness of 7 to 200 microns.
 7. The methodof claim 1, wherein the polymeric material comprises nylons, aramids,polyesters or combinations thereof.
 8. The method of claim 7, whereinthe polyesters comprise polyethylene terephthalate or polybutyrate. 9.The method of claim 1, wherein the papermaking belt is of a typeselected from the group consisting of: forming fabric, press fabric,belt press fabric, imprinting/structured fabric, dryer fabric and sheetsupport fabric.
 10. The method of claim 1, wherein the papermaking belthas a width of 40 to 400 inches.
 11. The method of claim 10, wherein thepapermaking belt has a width of 200 to 240 inches.
 12. The method ofclaim 1, wherein the papermaking belt has a caliper of 0.25 to 4.00 mm.13. The method of claim 12, wherein the papermaking belt has a caliperof 0.75 to 1.5 mm.
 14. The method of claim 1, wherein the papermakingbelt has an open area of 10 to 95 percent.
 15. The method of claim 14,wherein the papermaking belt has an open area of 40 to 60 percent. 16.The method of claim 1, wherein the papermaking belt has an airpermeability of 100 to 1000 cubic feet per minute as tested inaccordance with ASTM D737-96.
 17. The method of claim 16, wherein thepapermaking belt has an air permeability of 400 to 700 cubic feet perminute as tested in accordance with ASTM D737-96.
 18. The method ofclaim 4, wherein the 3D printing comprises laying down at least onelayer of material to form the papermaking belt with a pocket zoneconfigured to form three dimensional structures in a paper web.
 19. Themethod of claim 18, further comprising laying down at least one otherlayer of material to form the papermaking belt with a vacuum breakingzone configured to limit an amount of paper fibers pulled through thepocket zone.
 20. The method of claim 19, wherein the at least one vacuumbreaking zone comprises a plurality of vacuum breaking zones.
 21. Themethod of claim 18, further comprising laying down at least one otherlayer of material to form the papermaking belt with a valley pocketsupport zone configured to support pockets formed in the pocket zone.22. The method of claim 18, further comprising laying down at least oneother layer of material to form the papermaking belt with a shearmodulus control zone configured to enhance shear deformation of thepapermaking belt.
 23. A method of making a papermaking belt, comprising:laying down successive layers of polymeric material using a 3D printingprocess so as to form a unitary structure with zones corresponding tothe successive layers, wherein the zones comprise: a pocket zoneconfigured to form three dimensional structures in a paper web; and atleast one vacuum breaking zone configured to limit an amount of paperfibers pulled through the pocket zone, wherein the polymeric materialhas a Young's Modulus of 40 to 95 MPa.